Chinese and Russian scientists claim to make it rain or snow on command. But can we slow global warming with massive operations called geoengineering? A growing number of experts say yes—and that radically altering our environment may be our last, best hope of avoiding disaster. From orbiting space mirrors to artificial trees to brighter clouds, here's what's under discussion.

Flash PointsRisks vs. rewards. Like any untested tech-nology, geoengineering harbors unknown risks. An artificial cooling of the earth could disrupt global weather patterns, bringing drought and famine to parts of North Africa, India, and China.

What it would cost. Hoisting mirrors or sun shields into space could cost trillions, according to a September 2009 report by the United Kingdom's Royal Society. Stratospheric aerosols, which could block solar radiation and cool the earth, could cost tens of billions of dollars a year; cloud brightening, which reflects sunlight away from the earth, $2 billion a year. Expensive, yes, but to some economists, geo-engineering is worth pursuing. One well-regarded but controversial report projects that stratospheric aerosols could carry a benefit 27 times higher than their cost; it also suggests that marine cloud brightening could save $7.5 trillion by reducing the damage caused by global warming.

The "Greenfinger" scenario. David Victor, a climate policy expert at the University of California, San Diego, worries about the prospect of a single nation taking matters into its own hands. "It could be a Hail Mary pass by a country getting hammered by global warming," he says. A wealthy individual—Victor calls him a "lone Greenfinger"—could also choose to go it alone. To prevent unilateral action, experts need a framework for researching geoengineering and deciding, as Victor says, "who gets to put their hand on the thermostat." One such meeting, organized by the nonprofit Climate Institute in Washington, D.C., will take place this month.

Forward ThinkingContain the carbon. Removing carbon from the air and storing it underground, or reusing it for fuel, would help slow and possibly reverse global warming. This solution, says David Keith, a physicist at the University of Calgary, would cost considerably less than what we might spend converting carbon-fed electrical to rooftop solar power. England's Institution of Mechanical Engineers has even come up with a proposal to line highways with "artificial trees" that would collect carbon dioxide at rates far exceeding those of lazy natural trees and convert it into a form that's easily collected and stored.

Deflect, deflect, deflect. National Center for Atmospheric Research climatologist John Latham, along with University of Edinburgh engineer Stephen Salter, has designed a novel way of "brightening" clouds: a fleet of remote-controlled, wind-powered ships that would spray a fine seawater mist into marine clouds. "It's established that if you have a lot of little drops instead of a few big ones, then the clouds are more reflective," says Latham. They hope to increase that reflectivity by 10 percent, which, they say, would hold the earth's temperature steady until at least 2050. Keith is devising a reflective metal particle that could levitate itself above the ozone layer to reflect heat from the sun back into space, although his main focus remains on reflective aerosols. Washington-based Intellectual Ventures Lab, owned by former Microsoft guru Nathan Myhrvold, has proposed an 18-mile-long hose suspended from balloons that would pump liquefied sulfur dioxide (a gas emitted when volcanoes erupt) into the stratosphere.

Show them the money. Last year, a House of Representatives committee held its first hearing on climate engineering but shied away from funding any proposals. "We need a balanced, open, publicly funded research program," says Keith.

The Back-and-Forth …"A tiny investment in climate engineering might be able to reduce as much of global warming's effects as trillions of dollars spent on emissions reductions."—Bjorn Lomborg, the Copenhagen Consensus Center

"Geoengineering is a far-fetched, pie-in-the-sky dream to avoid having to make the emissions cuts we have to make now."—Michael Crocker, spokesman for Greenpeace

The Time Line874–853 bc: The prophet Elijah scales Mount Carmel in Israel and prays for rain. It pours.

3 comments:

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This blog is written by Professor Rob Elliott, an academic economist, with an interest in all things international and environmental..I am currently a Professor of International and Environmental Economics at the University of Birmingham..Find me at my homepage.

This weeks read

Following the recent workshop on the "Economics of the Stern Review" and the fuss caused by the "great global warming swindle" this book represents an excellent introduction to the topic. Chapter 6 is the chapter it all hinges upon.